Slings



L. M. CALDWELL SLINGS Jan. 5, 1960 Filed July 2l. 1953 3 Sheets-Sheet 1 leslie M CaZcZweZZ www@ Jan. 5, 1960 L. M. CALDWELL SLINGS 3 Sheets-Sheet 2 Filed July 21. 1953 ...III 13....:

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Jan. 5, 1960 L. M. CALDWELL 2,919,949

sLINGs Filed .July 21. 1953 s sheets-sheet s @Riv I United States Patent() SLINGS Leslie M. Caldwell, Rockford, Ill.

Application July 21, 1953, Serial No. 369,330

14 Claims. (Cl. 294-74) This invention relates to slings for use with hoisting equipment generally, and is more particularly concerned with slings which are self-equalizing and adapted to lock automatically to prevent tilting of the load when lifted.

A salient feature of the present slings is the' provision of a frame having a grooved saddle portion over which thekwire ropes attached to the load at their ends are slidable as the frame is hoisted, whereby to equalize the sling and lift the load evenly, the grooves in the saddle being inwardly tapered so that the ropes wedge therein under load to prevent slippage, and the saddle being'also equipped with a spring-loaded member at the middle thereof carrying rollers disposed crosswise with respect to the grooves to lift the ropes and free the same after a hoisting job is Vdone and the load is set down, the rollers serving also to assist in the equalizing of the sling by keeping the ropes free to slide one way or the other until the instant that the load is actually being lifted, when, of course, the'ropes will wedge in the grooves to prevent slippage.

Another important feature is the provision in connection with the frame of lwedge-blocks for use interchangeably merely as retainers disposed across the outer prtion of the grooves to prevent displacement of the ropes therefrom or as clamps to hold the ropes wedged inthe grooves, positively to prevent slippage, regardless of unequal loading of the legs of the sling, the blocks being provided on opposite sides of the middle portion of the frame where the spring-loaded rope freeing member is located and being used one at a time or both together in the rope clamping position, depending upon the need for special caution to prevent slippage in any given instance.

The invention is illustrated in the accompanying drawings, in which Fig. l is a front view of a sling made in accordance with my invention;

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plates 12 and 13' of semi-circular form to define saddle portions for support of sling ropes on opposite sides of the frame. Bolts for fastening these plates are indicated at 14 extending through holes 15 in plate 13 and threading inholes 16 in plate 12. Inwardly tapered annular shoulders 17 are provided on the plates 12 and 13 to provide the saddle portions mentioned and each of these shoulders defines with one face of the frame 11 a V- shaped groove 1S in which a wire rope or cable 19 is received for wedging engagement to prevent slippage when a large heavy casting or the like that is attached by means of hooks to the loposite ends of the ropes 19 is lifted, so that the load will not shift its position suddenly from a given desired angle. In operation, a sling made in accordance with the present invention is hung on the crane hook and the crane operator moves the sling with the crane to a point over the approximate center of gravity of the load. Then the two legs of the sling defined by the two ends of the rope or ropes 19, which have hooks (not shown) provided thereon for that purpose, are attached to the load and then, as the crane hook is raised, the legs of the sling adjust themselves in the grooves 18 to the proper length with respect to the frame 11 and plates 12 and 13 as the lifting starts. When the load is assumed 'by the two legs of the sling the ropes 19` are wedged firmly in the V-shaped grooves 18, thereby frictionally locking the sling in adjusted position, so that the load is lifted level or at whatever angle is desired.

When many identical loads are to be lifted so that fixed sling leg lengths once determined can be used again and again, the ropes 19 are adapted to be clamped in theirwedged position by means of U-shaped wedge-blocks Fig. 2 is a View partly in section on the line 2-2 of Fig. l and partly in side elevation showing one of the Wedge-blocks in full lines in rope-clamping position and in dotted lines in rope-retaining position;

Fig. 3 is a section on the line 3-3'of.Fig. l;

Fig. 4 is a view similar to Fig. 1 showing a modified or alternative construction; i

Figs. 5 and 6 are sections similar to Figs. 2 and 3, respectively, taken on the lines 5-5 and 6-6, respectively, of Fig. 4;

lFig. 7 is a view similar to Figs. 1 and 4 showing still another modified or alternative construction;

Fig. 8 is a side view of Fig. 7 with the position of the rope 19a indicated only in dotted lines, and

Figs. 9` and 10 are two views of one of the rope-gripping and retaining plates.

Similar reference numerals are applied to correspond- A'ing parts throughout the views.

Referring first to Figs. 1 to 3, the reference numeral frame, to the opposite sides of which are bolted wedge- 20 which straddle the arcuate lateral extensions 21' of theY frame 11 and are fastened by bolts 22 threaded in holes 23 provided therefor in the frame radially with respect to said arcuate extensions 21. There are two holes 24 and 25 at right angles to lone Aanother in the cross-portion 26 of ea-ch U-shaped wedge-block 20 and when the bolt 22 is entered in hole 25, as shown in Fig. 2, and at the left in Fig. 1, the legs 27 of the block 20 engage the ropes 19 holding them firmly clamped in their wedged position in the grooves 18 so that there is no danger of slippage. Up to two-thirds of the rated load may be carried on one leg of the sling'without slippage when the ropes 19' are clamped in this manner. When the bolts 22 are entered in the other hole 24, as shown at the right in Fig. 1 and in dotted lines in Fig. 2, the blocks 20 serve only to retain the ropes in the grooves against displacement. 20 are placed in the one or other positions to retain the ropes against displacement from the grooves 18 or to clamp the same in wedged position in the groves. The blocks are shown in the two different positions in Fig. 1 only for purposes of better illustration.

Two rollers 2S are movable vertically in cored-out portions 29 provided on the inner sides of the plates 12 and 13 on the vertical center line thereof and these rollers engage the ropes 19 on the under-side at the mid-point of their wedging engagement in the grooves 18, as clearly appears in Figs. 1 and 3, and are urged upwardly by means of a coiled compression spring 30 -so as to lift the ropes out of wedging engagement in the grooves and free them when they are no longer under load after a hoisting job is done and the load has been set down. The rollers 28 are carried on coaxial trunnions 31 projecting from opposite sides of a cross-head 32 that is rslidable vertically on a bolt 33, the shank of which extends through a vertical hole 34 provided in the cross-head 32, the frame 11 having its middle portion cut away, as indicated at 35, in register with the cored-out portions 29 in the plates 12 and 13' to provide operating clearance for the up and Usually, of course, both blocksY down movement of the cross-head 32, and a hole 36 being provided in the arch 37 over the cut-out portion 35 in the frame 11 to receive the upper end of the bolt 33 and provide support therefor. A nut 38 threaded on the lower end of the bolt 33 and adapted to be pinned or otherwise suitably locked to the bolt in adjusted position against accidental loosening provides abutment for the lower end of the spring 30 and holds this spring caged under a predetermined preload compression, even when the crosshead 32 is disposed at the upper end of the cut-out 35, the purpose being to insure enough spring pressure through rollers 28 in an upward direction on the ropes 19 at the middle of the saddle deiined by the plates 12 and 13 to insure freeing the ropes immediately when the same are not under load. This spring7 pressure in an upward direction on the ropes is obviously also of assistance during the equalization of the sling by keeping the ropes free to slide one way or the other until the instant that the load actually is lifted, when, of course, the ropes become wedged in the grooves 18 to prevent slippage. The upward spring pressure on rollers 28 is, of course, quite small in relation to the weight of most loads lifted.

In operation, the spring 30 keeps the rollers 28 normally raised with the cross-head 32 in engagement with the upper end of the cut-out portion 35 of frame 11, and, consequently, as the lifting starts, there is enough freedom of the ropes 19 in the grooves 18 to insure equalization of the two legs of the sling before the two legs are placed under tension. Then, as the crane hook continues to rise and the load is eventually lifted, the ropes 19 become more and more firmly wedged in the grooves 18, so that before the load is lifted to any appreciable height there will be no likelihood of the ropes slipping and the Vload changing its angle. As stated before, the crane operator locates the sling over the approximate center of gravity of the load, and, if he makes a mistake in his estimate the first time and he sees that he is accordingly placing too much load on one leg of the sling, he lowers the load to release the brake action on the ropes and moves the crane hook in the right direction to the correct position and the sling legs readjust themselves in the next lift. In most lifting, the blocks 2i) are disposed like the one shown at the right in Fig. 1, with the legs 27 in retracted position with respect to the grooves 18. Where many identical loads are to be lifted and fixed sling leg lenths are desirable, the blocks 2t) are removed from the position shown at the right in Fig. 1 and turned to the position shown at the left in Fig. 1 and fastened by means of bolts 22 clamping the ropes 19 in the wedged position. When the ropes are clamped in that way, up to two-thirds of the rated load may be carried on one leg of the sling Without slippage.

Referring next to Figs. 4, and 6, the sling shown in these figures is of closely similar construction in so far as everything but the rope clamping means is concerned, and, therefore, corresponding parts have been identified by the same numerals primed, the frame being numbered 11', wedge plates 12 and 13', and so forth. In this form, wedge-blocks 20a are guided in notches 39 provided therefor in the arcuate periphery of the wedge plates 12; and 13 and have bevelled faces 40 arranged for wedging engagement with the upper and outer sid of the ropes 19', as clearly appears in Fig. 5, so that when the blocks 253m are drawn toward each other by the tightening of bolts 22a, the ropes are clamped securely and there is no danger of slippage. Bolts 22a extend freely through holes 41 in the blocks Zita disposed on one side of the frame 11' and through registering holes 42 provided in the frame and are threaded in holes 43 disposed on the other side of the frame 11. With this construction, the operation is closely similar to that described before except that here the bolts 22a may be loosened when the blocks 20a are to serve only for retaining the ropes 19 in the grooves 18. However, when many identical loads are to be lifted and the sling leg lengths have once been determined and the operator wants to clamp the ropes to provide iixed sling leg lengths, it is only necessary to tighten the bolts 22a to accomplish this. When the bolts are tightened, the ropes 19 are clamped in their wedged position.

Referring finally to Figs. 7 to 10, the sling shown in these views is of much simpler and cheaper construction and designed to use only one wire rope or cable 19a in the groove 18a, there being only one wedge plate 12a bolted to one side of the frame 11a by bolts 14a. The rope 19t.' will wedge in the groove 18a after equalization of the two legs, similarly as in the other forms, and a vertical groove 44 is provided on the inner side of the plate 12a in which a ball 28 is provided seated on a coiled compression spring 34) that is carried on a plug 38 suitably secured in the lower end of the groove. A lug 45 extends from the peripheral portion of the plate at the middle and serves to retain the rope against accidental displacement from the groove 18a and thereby limit upward movement of the ball 28'. However, there are two rope retaining and locking plates Zibb which when disposed in the full-line position shown in Fig. 7 also serve to retain the rope against displacement from the groove, and these plates may be turned to the position shown in dotted lines and clamped by means of bolts 22b with their angular inner ends 46 in wedging engagement with the rope 19a so as to hold the rope firmly in wedged position. Each plate 20h has a hole 47 therein through which the cooperating bolt 22b extends freely, and holes 48 are provided in the frame 11a for threaded engagement of the bolts 22b therein, so that when the bolts are loosened the plates 2Gb may be turned freely, and then,

`when the plates have been properly positioned, they may be fastened by merely tightening the bolts. With this sling, therefore, the same general kind of operation is obtained as with the others, it being possible to retain the rope 19a against displacement using the same devices 'Ztlb which are adapted otherwise to be used in clamping the rope in a wedged position.

It is believed the foregoing description conveys a goo understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modications and adaptations.

I claim:

1. A sling, comprising a liftable load-carrying frame having non-rotatable means defining a substantially semicircular saddle portion thereon supporting the intermediate portion of a rope that is slung thereover and adapted to be attached at its ends at spaced points to an object to be lifted, the saddle portion receiving the rope in a V-shaped groove provided therein wherein the `rope wedges under load to prevent slippage, said rope being shiftable endwise relative to said frame in said groove by the load before wedging in the groove under load, and means mounted `on the frame radially outwardly relative to said saddle over the rope serving to retain the rope in the groove and movable inwardly for temporarily forcibly wedging the rope more tightly in the groove than it would otherwise be wedged by reason of the load alone and holding the same in such position, said means being operable manually from the radially outer side of said saddle to secure or release the rope.

2. A sling as set forth in claim 1, wherein the last mentioned means comprises a device attachable to the frame radially outwardly relative to said saddle selectively in either of two positions over said rope, in one of which positions it is adjustable radially inwardly with respect to g circular saddle portion thereonV supporting'the intermediate portion of a rope` that is slung thereover'throughout an included angle of approximately 90 and adapted to be attached at its ends at spaced points 'to an object to be lifted, the saddle portion receiving the rope in a V-shaped groove provided therein ywherein the rope Wedges under load to prevent slippage, said frame having a single substantially vertical bore provided centrally thereof, the upper end of which opens into the bottom of the V-shaped groove, and a single spring-pressed means disposed in said bore arranged to press upwardly on the middle portion of the wedged intermediate portion of the rope from below to loosen and free the same from said groove.

4. A sling comprising a liftable load-carrying frame having non-rotatable means defining a substantially semicircular saddle portion thereon supporting the intermediate portion of a rope that is slung thereover throughout an included angle of approximately 90 and adapted to be attached at its ends at spaced points to an object to be lifted, the saddle portion receiving the rope in a V-shaped groove provided therein wherein the rope wedges under load to prevent slippage, and spring pressed means mounted in said saddle under said rope resisting downward movement of the rope into wedged position in the groove adapted to loosen and free the rope from said groove when the rope is no longer under the tension of supporting an object attached to the ends thereof.

5. A sling as set forth in claim 4, including means for retaining said rope against displacement from the groove when free, said retaining means comprising a device attachable to the frame radially outwardly relative to said saddle selectively in either one of two positions over said rope, in one of which positions it is adjustable radially inwardly with respect to said saddle from the radially outer side of said saddle to secure the rope in wedged position in the groove more tightly than it might otherwise be wedged by reason of the loading alone, and in the other of which positions its serves only to retain the rope against displacement from the groove when free.

6. A sling comprising a liftable load-carryingrframe having non-rotatable means defining a substantially semicircular saddle portion thereon supporting the intermediate portion of a rope that is slung thereover throughout an included angle of approximately 90 and adapted to be attached at its ends at spaced' points to anv object to be lifted, the saddle portionV receiving the rope in a V- shaped groove provided therein wherein the rope wedges under load to prevent slippage, a roller disposed in the groove for rotation on an axis transversely thereof and having the rope riding thereon for free movement in either direction in the equalization of the sling preliminary to lifting an object, and spring means mounted in said saddle under said roller normally urging said roller upwardly whereby to resist downward movement of the rope into wedged position in the groove and loosen and free the rope from said groove when the rope is no longer under the tension of supporting an object attached to the ends thereof.

7. A sling, comprising a liftable load-carrying frame having non-rotatable means defining a substantially semicircular saddle portion thereon supporting the intermediate portion of a rope that is slung thereover throughout an included angle of approximately 90 and adapted to be attached at its ends at spaced points to an object to be lifted, the saddle portion receiving the rope in a V-shaped groove provided therein wherein the rope Wedges under load to prevent slippage, said frame having a single substantially vertical bore provided centrally thereof, the upper end of which opens into the bottom of the V-shaped groove, a single spring-pressed means disposed in said bore arranged to press upwardly on the middle portion of the wedged intermediate portion of the rope from below to loosen and free the same from said groove when the rope has little or no load thereon,

said rope beingA shiftable endwise relative to saidframe in said groove by the load before wedging in the groove under load, and means spaced circumferentially of said groove on opposite sides of said spring pressed means and mounted on the frame radially outwardly relative to said saddle over the rope serving to retain the rope in the groove and movable inwardly for temporarily forcibly wedging the rope more tightly in the groove than it would otherwise be wedged by reason of the load alone and holding the same in such position, said means being operable manually from the radially outer side of said saddle to secure or release the rope.

8. A sling comprising a liftable load-carrying frame having non-rotatable means defining a substantially semicircular saddle portion thereon supporting the intermediate portion of a rope that'is slung thereover throughout an included angle of approximately and adapted to be attached at its ends at spaced points to an object to be lifted, the saddle portion receiving the rope in a V-shaped groove provided therein'wherein the rope wedges under load to prevent slippage, a roller disposed in the groove substantiallyV midway between the ends thereof for rotation on an axis transversely thereof and having the rope riding thereon for free movement in either direction in the equalization of the sling preliminary to lifting an object, spring means mounted in said saddle under said roller normally urging said roller upwardly whereby to resist downward movement of the rope into wedged position in the groove and loosen and free the rope from said groovev when the rope is no longer under the tension of supporting an object attached to the ends thereof, saidrope being Ashiftable endwise relative to said frame in said groove by the load before wedging inthe groove under load, and means spaced circumferentially of said groove-on opposite sides of said spring pressed means and mounted on the frame radially outwardly relative to said'saddle over the rope serving to retain the rope in the groove and movable inwardly for temporarily forcibly wedging the rope more tightly in the groove than it would otherwise be wedged byreason of the load alone and holding the same in such position, said means being operable manually from the radially outer side of said saddle to secure or release the rope.

9. A sling comprising a liftable load-carrying frame having non-rotatable means defining substantially semicircular saddle portions on opposite sides thereof supporting intermediate portions of a pair of ropes that are slung over these saddle portions throughout an included angle of approximately 90 and are adapted to be attached at their ends at spaced points to an object to be lifted, the two ropes being adapted to support a load in balanced relationship to said frame, the saddle portions receiving the ropes in V-shaped grooves provided therein wherein the ropes wedge under load to prevent slippage, and spring pressed means mounted in said frame approximately at the middle of the aforesaid ninety degree (90) angle and operative substantially radially of the saddle portions against the under side of the ropes resisting downward movement of the ropes into wedged position in the grooves adapted to loosen and free the ropes from the grooves when the ropes are no longer under the tension of supporting an object attached to the ends thereof.

l0. A sling as set forth in claim 9, including means for retaining said ropes against displacement from the grooves when free, said retaining means comprising a device attachable to the frame radially outwardly relative to said saddle selectively in either one of two positions over said ropes, in one of which positions it is adjustable radially inwardly with respect to said saddle from the radially outer side of said saddle to secure the ropes in wedged position in the grooves more tightly than they might otherwise be wedged by reason of the loading alone, and inthe other of which positions it serves 'if Only to retain the ropes against displacement from the grooves when free.

11. A sling comprising a liftable load-carrying frame having non-rotatable means defining substantially semicircular saddle portions on opposite sides thereof supporting intermediate portions of a pair of ropes that are slung over these saddle portions throughout an included angle of approximately 90 and are adapted to be attached at their ends at spaced points to an object to be lifted, the two ropes being adapted to support a load in balanced relationship to said frame, the saddle portions receiving the ropes in V-shaped grooves provided therein wherein the ropes wedge under load to prevent slippage, rollers disposed in the grooves for rotation on an axis transversely thereof and having the ropes riding thereon for free movement in either direction in the equalization of the sling preliminary to lifting an object, a cross-head between the rollers supporting the same for rotation and up and down movement at the middle of the aforesaid 90 angle, and spring means mounted in said saddle under said cross-head normally urging said cross-head upwardly whereby to resist downward movement of the ropes into wedged position in the grooves and loosen and free the ropes from said grooves when the ropes are no longer under the tension of supporting an object attached to the ends thereof.

12. A sling comprising a liftable load-carrying frame having non-rotatable means defining substantially semicircular saddle portions on opposite sides thereof supporting intermediate portions of a pair of ropes that are slung over these saddle portions throughout an included angle of approximately 90 and are adapted to be attached at their ends at spaced points to an object to be lifted, the two ropes being adapted to support a load in balanced relationship to said frame, the saddle portions receiving the ropes in V-shaped grooves provided therein wherein the ropes are slidable in either direction relatively freely before loading but wedge under load to prevent slippage, said ropes being both shiftable endwise relative to said frame in said grooves by the load before wedging in the grooves under load, and means mounted on the frame radially outwardly relative to said saddle over the ropes serving to retain the ropes in the grooves and movable inwardly for temporarily forcibly wedging the ropes more tightly in the grooves than they would otherwise be wedged by reason of the load alone and holding the same in such position, said means being operable manually from the radially outer side of said saddle to secure or release the ropes.

13. A sling as set forth in claim 12, wherein the last mentioned means comprises a device attachable to the frame radially outwardly relative to said saddle selectively in either of two positions over said ropes, in one of which positions it is adjustable radially inwardly with respect to said saddle from the radially outer side of said saddle to secure the ropes in wedged position in the grooves more tightly than they might otherwise be wedged by reason of the loading alone, and in the other of which positions it serves only to retain the ropes'againstdisplacement from the grooves when free.

14. A sling comprising a liftable load-carrying frame having non-rotatable means defining substantially semicircular saddle portions on opposite sides thereof supporting intermediate portions of a pair of ropes that are slung over these saddle portions throughout an included angle of approximately and are adapted to be attached at their ends at spaced points to an object to be lifted, the two ropes being adapted to support a load in balanced relationship to said frame, the saddle portions receiving the ropes in V-shaped grooves provided therein wherein the ropes are slidable in either direction relatively freely before loading but wedge under load to prevent slippage, spring pressed means mounted in said saddle under said ropes and mounted in said frame approximately at the middle of the aforesaid ninety degree (90) angle and operative substantially radially of the saddle portions against the under side of the ropes resisting downward movement of the ropes into wedged position in the grooves adapted to loosen and free the ropes from the grooves when the ropes are no longer under the tension of supporting an object attached to the ends thereof, said ropes being shiftable endwise relative to said frame in said grooves by the load before wedging in the grooves under load, and means spaced circumferentially of said grooves on opposite sides of said spring pressed means and mounted on the frame radially outwardly relative to said saddle over the ropes serving to retain the ropes in the grooves and movable inwardly for temporarily forcibly wedging the ropes more tightly in the grooves than they would otherwise be wedged by reason of the load alone and holding the same in such position, said means being operable manually from the radially outer side of said saddle to secure or release the ropes.

References Cited in the le of this patent UNITED STATES PATENTS 1,222,048 Sunderland Apr. 10, 1917 2,277,424 White Mar. 24, 1942 2,555,501 Morgan June 5, 1951 2,620,218 Morith Dec. 2, 1952 2,623,732 Morgan Dec. 30, 1952 2,638,184 Sturdivant May 12, 1953 2,661,231 Caldwell Dec. l, 1953 FOREIGN PATENTS 108,982 England Aug. 30, 1917 

